Whoa, I just got a basic Python wrapper around ngtcp2 [server only] functional. Lots of error handling and edge cases need to be implemented.

The test that is working is a client (aioquic) connects, opens a stream, both sides send some data, and confirms that the other side received the data.

I really didn't think my last set of changes would make things work, I expected to hit some unimplemented parts.

TODO:
```
$ grep NotImplementedError ngtcp2.py | wc -l
15
```

#Python #ngtcp2

Code coverage isn't great, but isn't terrible either:
```
Name Stmts Miss Cover Missing
------------------------------------------------------
ntunnel/ngtcp2.py 866 145 83%
```

There needs to be a LOT more tests written before this will be close to being done. For example, datagrams are unimplemented.

The best thing is that most of the C interface framework is done.